The 28 year-old was a no-show at his half-sister’s birthday celebrations.

Rob Kardashian has broken his social media silence on Instagram following claims he “refused” to go to half-sister Kylie Jenner ‘s 18th birthday party on Sunday night, posting two random images to his account.

The 28 year-old, who has barely been seen in public over the last few years as he struggles with personal demons, was the only member of the family not to attend the blow-out celebrations in Hollywood on Sunday night.

Kylie partied at The Nice Guy restaurant before heading to Bootsy Bellows with boyfriend Tyga, sisters Kim, Khloe, Kourtney and Kendall and even her parents Kris and Caitlyn Jenner managed to play nice for the evening.

On Monday all the Kardashian/Jenners sent birthday love to Kylie on social media, but not Rob.

He did let followers know that he was in a Miami Vice kind of “mood” though, posting a pic of Colin Farrell from the 2006 re-vamp and then a bizarrely a picture of Paul Newman from his food range with the caption: “RIP”.

Rob didn’t mention his sister in the posts or address the claims he’s distancing himself from his famous family. A source on Monday claimed he’d flat out refused to attend any of Kylie’s weekend long birthday celebrations.

“Rob refused to do anything for Kylie’s birthday. He is invited to everything and he refuses to come to anything.” a source told RadarOnline.

“He’s just ignoring everyone. His mom, his sisters. He just doesn’t care.”

It isn’t the first time Rob has missed a huge family event. Last year he flew home from Paris in the middle of Kim Kardashian and Kanye West’s wedding celebrations, missing their big day in Florence.

While Rob has a strained relationship with big sister Kim, he’s known to be incredibly close to Kylie so skipping this bash has surprised fans even more.

Maybe Rob is just sick of the circus around his famous family, one Fox News anchor even had an on-air meltdown over the attention the Kardashians receive on Monday.